He was on 45%, while Mr Gingrich was on 25%, former Pennsylvania Senator Rick Santorum 11% and Texas Congressman Ron Paul 9%.

The Trump development may at least give Mr Romney’s campaign some respite from negative publicity over ill-chosen remarks he made about the poor on Wednesday morning.

During an interview with CNN, the private equity tycoon said: “I’m not concerned about the very poor. We have a safety net there. If it needs repair, I’ll fix it. I’m not concerned about the very rich. They’re doing just fine. I’m concerned about the very heart of America, the 90-95% of Americans who are struggling.”

Mr Gingrich led critics in pouncing on his rival’s remarks about the poor, in an attempt to portray him as out of touch with the lives of ordinary voters.

Mr Romney later told reporters on his plane: “Of course I’m concerned about all Americans… poor, wealthy, middle class, but the focus of my effort will be on middle income families who I think have been most hurt by the Obama economy.”

Nevada’s caucuses on Saturday are the next contest in the state-by-state process of picking a Republican nominee to challenge Democratic President Barack Obama in 6 November’s general election.

The Silver State offers 28 delegates, out of 1,144 needed to clinch the presidential nomination at August’s Republican convention.